A novel relay selection scheme in multi-antenna cooperative systems

This paper considers the cooperative schemes where the source, relay and the destination are all multi-antenna terminals. Zero-forcing equalization and maximum ratio combining technique are employed in this scheme. We extend the classical selection relaying into the multi-antenna setup. Based on a predefined threshold, the source decides to cooperate only when it needs help. The source picks only one relay to cooperate with and the optimal relay is the one which has the maximum instantaneous value of the relay´s metric, which is a modified version of the harmonic mean function of its source-relay (S-R) and relay-destination (R-D) channel gains. We also presented some simulation results to verify the proposed relay selection scheme.